Low density polyethylene (ldpe) - asphaltene composition and method of preparation

ABSTRACT

A low density polyethylene-asphaltene composition and a method of preparation of the low density polyethylene-asphaltene composition, the composition comprising an asphaltene, wherein the asphaltene is extracted from at least one of a heavy atmospheric residue, oil sands, bitumen, and biodegraded oils, and a weight percent of the asphaltene is 0.1%-25% relative to a total weight of the composition; and a low density polyethylene polymer with a density of 0.9 g/cm 3 -0.95 g/cm 3 . The asphaltene and the low density polyethylene polymer are uniformly dispersed throughout the low density polyethylene-asphaltene composition, the low density polyethylene-asphaltene composition has a weight loss onset 4° C.-20° C. higher than an average weight loss onset of the low density polyethylene polymer, and the low density polyethylene-asphaltene composition has a degree of crystallinity of 27%-34%.

BACKGROUND OF THE INVENTION Technical Field

The present invention relates to a composition or composite havingasphaltene filler and low density polyethylene.

Description of the Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Polymer composites are mixtures of polymers with inorganic or organicadditives. Thus, polymer composites contain two or more components andtwo or more phases. A modified polymer matrix is formed by incorporationof fillers and has micro-and macrostructures which possess uniquephysiochemical properties. Therefore, the main reasons behind usingthese fillers include enhancement of properties, overall cost reductionas relatively lesser amount of polymeric material is required, andimproved processing characteristics which reduces the required energyand time.

The additives for polymer composites have been variously classified asreinforcements, fillers, or reinforcing fillers. Reinforcements, beingmuch stiffer and stronger than the polymer, usually increase its modulusand strength. Thus, mechanical property modification may be consideredas their primary function, although their presence may significantlyaffect thermal expansion, transparency, thermal stability, and so on.However, most fillers are considered as additives, which, because oftheir unfavorable geometrical features, surface area, or surfacechemical composition, may only moderately increase the modulus of thepolymer, whereas strength (tensile, flexural) remains unchanged or evendecreased. Depending on the type of filler, other polymer properties canbe affected; for example, melt viscosity can be significantly increasedthrough the incorporation of fibrous materials. On the other hand, moldshrinkage and thermal expansion may be reduced, a common effect of mostinorganic fillers.

In view of the forgoing, one objective of the present invention is toprovide a composition or composite comprising asphaltenes and LowDensity Polyethylene (LDPE).

BRIEF SUMMARY OF THE INVENTION

According to a first aspect a low density polyethylene-asphaltenecomposition having an asphaltene, wherein the asphaltene is extractedfrom at least one of a heavy atmospheric residue, oil sands, bitumen,and biodegraded oils, and a weight percent of the asphaltene is 0.1%-25%relative to a total weight of the composition, and a low densitypolyethylene polymer with a density of 0.9 g/cm³−0.95 g/cm³. Theasphaltene and the low density polyethylene polymer are uniformlydispersed throughout the low density polyethylene-asphaltenecomposition, the low density polyethylene-asphaltene composition has aweight loss onset 4° C.-20° C. higher than an average weight loss onsetof the low density polyethylene polymer, and the low densitypolyethylene-asphaltene composition has a degree of crystallinity of27%-34%.

In some embodiments, the low density polyethylene-asphaltene compositionhas a peak melting point of 110° C.-123° C.

In some embodiments, the low density polyethylene-asphaltene compositionhas a heat of fusion of 84 J/g-93 J/g.

In some embodiments, the low density polyethylene-asphaltene compositionhas a storage modulus of 8%-25% greater than an average storage modulusof the low density polyethylene polymer at a temperature of 22° C.-25°C.

In some embodiments, the low density polyethylene-asphaltene compositionhas a tensile strength of 3%-5% greater than an average tensile strengthof the low density polyethylene polymer.

In some embodiments, a weight percent of the low density polyethylenepolymer is 75%-99.9% relative to the total weight of the composition.

According to a second aspect, a method to prepare a low densitypolyethylene-asphaltene composition including melting a low densitypolyethylene polymer to form a melted low density polyethylene polymer,adding an asphaltene and mixing, wherein the asphaltene is asemi-crystalline solid, to the melted low density polyethylene polymerat a mixing temperature of 165° C.-200° C. to form a melted low densitypolyethylene-asphaltene blend, pressing the melted low densitypolyethylene-asphaltene blend to form a pressed low densitypolyethylene-asphaltene blend, and cooling the pressed low densitypolyethylene-asphaltene blend to a cooled temperature of 22° C.-30° C.to form the low density polyethylene-asphaltene composition.

In some implementations of the method, the low density polyethylenepolymer is melted at a melting temperature of 165° C. to 200° C.

In some implementations of the method, the melted low densitypolyethylene-asphaltene blend is pressed for a duration of 1 min-10 min.

In some implementations of the method, the melted low densitypolyethylene-asphaltene blend is pressed at a pressing temperature of175° C.-200° C.

In some implementations of the method, the melted low densitypolyethylene-asphaltene blend is pressed at a pressure of 7 MPa-10 MPa.

In some implementations of the method, the asphaltene is extracted fromat least one of a heavy atmospheric residue, oils sands, bitumen, andbiodegraded oils.

In some implementations of the method, the asphaltene is asemi-crystalline solid.

In some implementations of the method, the low densitypolyethylene-asphaltene composition has a peak melting point of 110°C.-123° C.

In some implementations of the method, the low densitypolyethylene-asphaltene composition has a degree of crystallinity of27%-34%.

In some implementations of the method, the low densitypolyethylene-asphaltene composition has a heat of fusion of 84 J/g-93J/g.

In some implementations of the method, the low densitypolyethylene-asphaltene composition has a weight loss onset 4° C.-20° C.higher than an average weight loss onset of the low density polyethylenepolymer.

In some implementations of the method, the low densitypolyethylene-asphaltene composition has a storage modulus of 8%-25%greater than an average storage modulus of the low density polyethylenepolymer at a temperature of 22° C.-25° C. and the low densitypolyethylene-asphaltene composition has a tensile strength of 3%-5%greater than an average tensile strength of the low density polyethylenepolymer.

The foregoing paragraphs have been provided by way of generalintroduction, and are not intended to limit the scope of the followingclaims. The described embodiments, together with further advantages,will be best understood by reference to the following detaileddescription taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a FTIR spectrum of LDPE and LDPE/asphaltenes composites withvarying amounts of asphaltenes;

FIG. 2 is a series of DSC scans of pristine LDPE and its composites withvarious amounts of asphaltenes obtained during the second heating toevaluate the melting temperature;

FIG. 3 is a DSC thermogram of pristine LDPE and its composites withvarious amounts of asphaltenes obtained during cooling to estimate meltcrystallization;

FIG. 4 is an XRD spectrum of LDPE and LDPE/asphaltene composites withvarious amounts of the asphaltene;

FIG. 5A is an exemplary SEM image of LDPE/asphaltenes composite having 0wt % asphaltenes;

FIG. 5B is an exemplary SEM image of LDPE/asphaltenes composite having2.5 wt % asphaltenes;

FIG. 5C is an exemplary SEM image of LDPE/asphaltenes composite having 5wt % asphaltenes;

FIG. 5D is an exemplary SEM image of LDPE/asphaltenes composite having7.5 wt % asphaltenes;

FIG. 5E is an exemplary SEM image of LDPE/asphaltenes composite having10 wt % asphaltenes;

FIG. 5F is an exemplary SEM image of LDPE/asphaltenes composite having15 wt % asphaltenes;

FIG. 6A is an exemplary thermal stability graph of neat LDPE and itscomposites with different amounts of asphaltenes;

FIG. 6B is an exemplary thermogravimetric analysis graph of neat LDPEand its composites with different amounts of asphaltenes;

FIG. 7 is an exemplary graph of tensile strength of the composition withdifferent amount of asphaltenes;

FIG. 8A is an exemplary DMA graph of the storage modulus, E′ obtainedfrom DMA measurements;

FIG. 8B is an exemplary DMA graph of the phase angle and the tanδ=E″/E′obtained from DMA measurements; and

FIG. 8C is an exemplary DMA graph of the loss modulus, E″ obtained fromDMA measurements.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Throughout the specification ranges may be expressed herein as from“about” one particular value, and/or to “about” another particularvalue. When such a range is expressed, another aspect includes from theone particular value and/or to the other particular value. Similarly,when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms anotheraspect. It will be further understood that the endpoints of each of theranges are significant both in relation to the other endpoint, andindependently of the other endpoint.

According to a first aspect a low density polyethylene-asphaltenecomposition having an asphaltene, wherein the asphaltene is extractedfrom at least one of a heavy atmospheric residue, oil sands, bitumen,and biodegraded oils. More specifically, the asphaltene of the presentdisclosure may be extracted from Arab heavy atmospheric residue. The lowdensity polyethylene-asphaltene composition described by the presentdisclosure may also be referred to interchangeably as a low densitypolyethylene-asphaltene composite. Asphaltene, as used herein, differsfrom asphalt, and refers to molecular substances that may be found incrude oil, along with resins, aromatic hydrocarbons, and saturates.Asphaltenes are composed mainly of polyaromatic carbon ring units whichmay contain one or more of an oxygen, nitrogen, and sulfur heteroatoms,optionally combined with trace amounts of heavy metals, particularlychelated vanadium and nickel, and aliphatic side chains of variouslengths. Asphaltene is insoluble in light n-paraffinic hydrocarbon, i.e.n-heptane, but is soluble in toluene.

Asphalt is a colloidal system similar to petroleum, but with lightermolecules removed. Asphalt can be fractionated into 4 major components:saturates, aromatics, resins and asphaltenes. The fractionated part ofsaturates and aromatics is considered as gas oil. Polarity of these fourfractions can be arranged as:

saturates<aromatics<resin<asphaltenes.

Asphalt is soluble in carbon disulfide. Due to the aromatics, an asphaltis heavier than its constituent asphaltenes.

Asphaltenes generally impede producing, transporting and refining ofcrude oil resources for a variety of reasons. Mitigation of deleteriouseffects brought on by the inclusion of asphaltenes during hydrocarbonprocessing requires a thorough knowledge of the chemical and physicalproperties of asphaltenes. In addition, the heavy ends of crude oilshave many familiar applications related to protective coatings and roadpaving which can be enhanced by judicious application of asphaltenescience. It is accepted that the asphaltene structure is composed byaromatic rings, alkane chains and cyclic alkanes with heteroatoms withinthe asphaltene structure, as described above. Two types of structureshave been postulated: the “continent” or island structure (a) and the“archipelago” structure (b).

The continent structure (a) represents asphaltene as relatively flatdisk shape molecules with a dominantly aromatic core (usually consistingof more than seven rings) and a periphery of aliphatic chains. Thearchipelago structure (b) may consist of small aromatic groups (up tofour rings) which may be connected to each other by aliphatic chainswith carbon numbers up to 24. Gel permeation, thermal degradation,oxidation and angle neutron scattering show evidence of this structure.See Powers, Diana P. (2014) “Characterization and AsphaltenePrecipitation Modeling of Native and Reacted Crude Oils,” (Doctoralthesis) University of Calgary, Calgary, Alberta, Canada, incorporatedherein by reference in its entirety.

An asphaltene source may be characterized by a quantity of saturates,aromatics, and resins which may be fractionated. Different sources havedifferent quantities of saturates, aromatics, resins, and asphaltenes.For example, from western Canadian oils saturates may be from 8 to 17 wt% relative to the total oil, aromatics may be from 36 to 44 wt %relative to the total oil, resins may be from 18 to 27 wt % relative tothe total oil, asphaltenes may be from 15 to 20 wt % relative to thetotal oil; from Arabian oils saturates may be from 22 to 25 wt %relative to the total oil, aromatics may be from 26 to 50 wt % relativeto the total oil, resin may be 10 to 18 wt % relative to the total oil,and asphaltenes may be 30 to 36 wt % relative to the total oil; and fromSumatran oils, saturates from 44 to 46 wt % relative to the total oil,aromatics may be from 30 to 33 wt % relative to the total oil, resinsmay be from 15 to 17 wt % relative to the total oil, asphaltenes may befrom 7 to 10 wt % relative to the total oil. Oils from different regionshave different characterizations based on saturates, aromatics, andresins, and asphaltenes, thus the asphaltenes extracted from thesesources also has a different composition. Asphaltenes extracted fromCalifornian oil may contain 1.9 to 2.2 wt % of nitrogen, 7 to 8.4 wt %of sulfur, and 2.4 to 2.7 wt % of oxygen relative to the total weight ofthe asphaltene; the asphaltene extracted from Canadian oil may contain1.2 to 1.4 wt % nitrogen, 0.4 to 0.5 wt % of sulfur, and 2.1 to 2.7 wt %of oxygen, relative to the total weight of the asphaltene; theasphaltene extracted from Arabian heavy oil may contain 0.9 to 1.8 wt %of nitrogen, 7.5 to 8.1 wt % of sulfur, 1.9 to 2.6 wt % of oxygen,relative to the total weight of the asphaltene. Further, metal contentmay distinguish asphaltenes obtained from the above mentioned regions aswell. For example, asphaltenes extracted from Californian oil maycontain 340 to 410 ppm of nickel, 930 to 1100 ppm of vanadium, and 11.9to 1800 ppm of sodium relative to the total volume of the asphaltene;the asphaltene extracted from Canadian oil may contain 19 to 28 ppm ofnickel, 42 to 48 ppm of vanadium, and 43 to 1800 ppm of sodium, relativeto the total volume of the asphaltene; the asphaltene extracted fromArabian heavy oil may contain 350 to 410 ppm of nickel, 1000 to 1200 ppmof vanadium, and 27 to 25,000 ppm of sodium, relative to the totalvolume of the asphaltene.

The average molecular weight of asphaltene may be on the order of 700g/mol-1300 g/mol. Recent studies have shown that asphaltenes may startforming nanoaggregates at concentrations lower than 30 μg/ml-70 μg/ml.The average nanoaggregate molecular weight in solution with tolueneappears to consist of two to six monomers per aggregate according tosome studies, although they may range in size up to 30,000 g/mol or even100,000 g/mol according to other studies.

The presently disclosed composition includes a weight percent of theasphaltene relative to a total weight of the composition of about0.1%-25%, about 0.2%-15%, about 0.5%-10%, about 1%-8%, preferably about2%-7%, more preferably about 3%-6%, or most preferably about 4%-5%. Thecomposition includes a low density polyethylene polymer, wherein the lowdensity polyethylene (LDPE) polymer is a density of about 0.9 g/cm³-0.95g/cm³ or about 0.92 g/cm³-0.93 g/cm³. The LDPE may have a melt index of1.5-2.7, 1.6-2.6, 1.7-2.5, and 1.8-2.4 and may have an average MW of70,000 to 100,000, 75,000 to 95,000, or 80,000 to 90,000. The asphalteneand the LDPE polymer are uniformly dispersed throughout the low densitypolyethylene-asphaltene composition.

In one embodiment, the composition consists of low density polyethyleneand the asphaltene.

The addition of asphaltenes to low density polyethylene may form aprotective layer (thermal shield) around the polymer molecules whichdelays the degradation induced by heat and acts as a thermal barrierlimiting the emission of the gaseous degradation products, which mayresult in an increase in the thermal stability of the material, alsoknown as an increase in the weight loss onset. The low densitypolyethylene-asphaltene composition has a weight loss onset relative toan average weight loss onset of the LDPE polymer of about 4° C.-20° C.higher, about 5° C.-18° C. higher, about 6° C.-16° C. higher, or about7° C.-14° C. higher. The homogeneous dispersion of asphaltenes mayresult in trapping the volatilizing matrix from escape to theatmosphere. The addition of asphaltenes to the low density polyethylenemay generate a nucleating effect of asphaltenes in the LDPE matrix. Anincrease in the degree of crystallinity was observed in the low densitypolyethylene-asphaltene composition relative to the LDPE. The additionof asphaltenes to the LDPE results in the low densitypolyethylene-asphaltene composition having a degree of crystallinityhigher than the LDPE polymer by about 27%-34%, about 28%-33%, about29%-32%, or about 30%-31%.

In some embodiments, the low density polyethylene-asphaltene compositionmay have an increased gel permeation chromatography branching indexrelative to LDPE that is about 1%-20% higher, about 2%-15% higher, about5%-10% higher, or about 7%-8% higher.

In some embodiments, the low density polyethylene-asphaltene compositionhas a peak melting point of about 110° C.-123° C., about 112° C.-120°C., or about 114° C.-118° C. The peak melting point may be measured bydifferential scanning calorimetry (DSC). DSC is a thermoanalyticaltechnique in which the difference in the amount of heat required toincrease the temperature of a sample and reference is measured as afunction of temperature. Both the sample and reference are maintained atnearly the same temperature throughout the experiment. The DSCmeasurements may be used to derive heat of fusion information as well.In some embodiments, the low density polyethylene-asphaltene compositionhas a heat of fusion of about 84 J/g-93 J/g, about 85 J/g-90 J/g, orabout 86 J/g-89 J/g.

In some embodiments, the low density polyethylene-asphaltene compositionhas a storage modulus relative to an average storage modulus of the lowdensity polyethylene polymer at a temperature of about 22° C.-25° C. orabout 23° C.-24° C., of about 8%-25% greater, about 10%-20% greater,about 12%-18% greater, or about 15%-16% greater.

In some embodiments, the low density polyethylene-asphaltene compositionhas a tensile strength relative to an average tensile strength of thelow density polyethylene polymer of about 3%-5% greater or about3.5%-4.5% greater. The tensile strength may be measured by a dynamicmechanical analysis (DMA), which is a technique useful for studying theviscoelastic behavior of polymers. A sinusoidal stress is applied andthe strain in the material is measured, allowing one to determine aratio of stress to strain.

In some embodiments, a weight percent of the low density polyethylenepolymer relative to the total weight of the composition is about75%-99.9%, about 80%-95%, about 85%-90%, or about 87%-88%.

In some embodiments, the low density polyethylene-asphaltene compositionmay further include high density polyethylene (HDPE) polymer of adensity of about 0.95 g/cm³-0.99 g/cm³ or 0.96 g/cm³-0.98 g/cm³, alinear low density polyethylene (LLDPE) polymer of a density of 0.90g/cm³-0.93 g/cm³ or 0.91 g/cm³-0.92 g/cm³, a polystyrene polymer, or apolypropylene polymer in a weight percent relative to the composition ofabout 0.1%-10%, about 0.5%-8%, about 1%-5%, or about 2%-4%. The HDPE,LLDPE, polystyrene, or the polypropylene polymers may be included totune modulus and strength, thermal expansion, transparency, thermalstability, and other properties understood by those familiar in the art.

In some embodiments, the low density polyethylene may include, but isnot limited to pure LDPE, a reinforced LDPE, such as carbon-fiberreinforced LDPE, glass fiber reinforced LDPE, or natural fiberreinforced LDPE, a nanoparticle-low density polyethylene composite, suchas a graphite-LDPE composite, a silica nanoparticle-LDPE composite, oran alumina nanoparticle-LDPE composite, branched LDPE having long-chainbranches or short chain branches.

A method to prepare a low density polyethylene-asphaltene compositionbegins by melting a low density polyethylene polymer to form a meltedlow density polyethylene polymer. In some implementations of the method,the melting of the low density polyethylene polymer is at a meltingtemperature of about 165° C. to 200° C., about 170° C. to 190° C., about175° C. to 185° C., or about 178° C. to 182° C. In some implementationsof the method, the melting process further includes mixing in anindustrial plastic mixer having both heating and mixing capabilitiessimultaneously. A rotor speed during mixing may be at about 40 rpm-80rpm, about 50 rpm-70 rpm, or about 55 rpm-65 rpm and may be continuousfor a duration of about 1 minutes-10 minutes, about 2 minutes-8 minutes,or about 4 minutes-6 minutes.

The melting is followed by adding an asphaltene to the melted lowdensity polyethylene polymer and mixing. In some implementations of themethod, the asphaltene is extracted from at least one of a heavyatmospheric residue, oils sands, bitumen, and biodegraded oils. In someimplementations of the method, the asphaltene is a semi-crystallinesolid. A semi-crystalline solid may be described as having a highlyordered molecular structure with sharp melt points. Semi-crystallinesolids may not gradually soften with a temperature increase, instead,semi-crystalline materials may remain solid until a given quantity ofheat is absorbed and then rapidly change into a low viscosity liquid.The asphaltene may be a semi-crystalline solid when it is to be added tothe melted low density polyethylene polymer or a molten polymer. Theasphaltene employed in the preparation is as described herein. Uponadding the semi-crystalline asphaltene to the melted low densitypolyethylene polymer, the mixing begins at a rotor speed of about 40rpm-80 rpm, about 50 rpm-70 rpm, or about 55 rpm-65 rpm for a durationof about 3 minutes to 10 minutes or about 5 minutes to 8 minutes. Themixing temperature during the adding of the semi-crystalline asphalteneto the melted low density polyethylene polymer may be about 165° C.-200°C., about 170° C.-190° C., about 175° C.-185° C., or about 178° C.-182°C. Upon adding the semi-crystalline asphaltene and mixing thesemi-crystalline asphaltene into the melted low density polyethylenepolymer a melted low density polyethylene-asphaltene blend is formed. Insome implementations of the method, the melting and the adding andmixing of the asphaltene may occur simultaneously.

In some implementations of the method, the melting and the mixing may beaccomplished by equipment such as a Brabender Plasti-Corder® Lab-Stationor twin screw extruders (i.e. a mini-compounder, lab-compounder), asingle-screw extruder. Commercially, twin-screw extruders are generallyutilized. Other apparatus and components may include, withoutlimitation, rollers, BANBURY® mixtures and kneaders. Regardless, mixersproviding high-shear efficiency are especially useful. Both batch andcontinuous processing can be employed. Such apparatus, components,operation and parameters thereof may be understood by those skilled inthe art.

Following the formation of the melted low densitypolyethylene-asphaltene blend, the melted low densitypolyethylene-asphaltene blend may be pressed to foim a pressed lowdensity polyethylene-asphaltene blend. In some implementations of themethod, the pressing is at a pressure of about 7 MPa-10 MPa, about 7.5MPa-9.5 MPa, or about 8 MPa-9 MPa. In some implementations, the meltedlow density polyethylene-asphaltene blend is pressed for a duration ofabout 1 min-10 min, about 2 min-7 min, or about 4 min-5 min. In someimplementations of the method, the pressing is at a pressing temperatureof about 175° C.-200° C., about 175° C.-195° C., or about 180° C.-190°C. In some implementations, the pressing may be directed into a mold toform a shape with the low density polyethylene-asphaltene blend. Theblend may be formed into sheets, pellets, solid shapes, or hollowshapes.

Upon forming the pressed low density polyethylene-asphaltene blend, theblend is cooled to a temperature of about 22° C.-30° C., about 22°C.-30° C. The cooling may be accomplished by passive cooling, such ascooling in ambient air to dissipate heat, or via active cooling methodssuch as industrial fans, cooling coils, dipping in cooling water, orrefrigeration. The cooling forms the low density polyethylene-asphaltenecomposition. In some implementations, a rate of cooling is about 0.5°C./min-3° C./min, about 0.75° C./min-2.5° C./min, about 1° C./min-2°C./min, or about 1.25° C./min-1.5° C./min.

The low density polyethylene-asphaltene composition resulting from theabove described method of preparation has a peak melting point, a degreeof crystallinity, a heat of fusion, a weight loss onset, a storagemodulus, and a tensile strength as described herein.

The low density polyethylene-asphaltene composition and variationsdescribed in the present disclosure may have application in roofingadhesives, tar-replacements, roofing underlayment, or concrete mixfillers.

The examples below are intended to further illustrate the low densitypolyethylene-asphaltene composition and are not intended to limit thescope of the claims.

EXAMPLE 1

The present example discloses a use of asphaltenes as an additive to LowDensity Polyethylene (LDPE). Several composites of LDPE with differentamounts of Asphaltenes were prepared by melt-mixing. The chemicalstructure of the composites was studied with Fourier Transform Infra-Red(FTIR) spectroscopy, crystalline characteristics with X-ray Diffraction(XRD), thermal properties (such as melting point or relativecrystallinity) by DSC, mechanical tensile properties with Instrondynamometer, while theimal degradation with Thermogravimetric analysis(TGA). The objective was to find new uses of a by-product of thepetroleum refinery industry in possibly improving the properties of acommodity polymer.

The present disclosure is related to our U.S. Pat. No. 9,018,285, Apr.28, 2015 and Patent application, Siddiqui, M. N. “Free Radical InitiatedMethyl Methacrylate-Arabian Asphaltene Polymer Composites”, patentapplication Ser. No. 14/155913, Jan. 15, 2014, and Siddiqui, M. N., “APolypropylene-Asphaltene Composite and Methods Thereof” Patentapplication—U.S. Pat. No. 450,371 in process, each incorporated hereinby reference in its entirety.

Experimental Details Preparation of LDPE/Asphaltene Composites

LDPE was melt blended with different weight percentages of asphaltenes(“the filler”) as filler using a Brabender Plasti-Corder® (Brabender®GmbH & Co., Germany) at 170° C. for 10 min at a rotor speed of 60 rpm.The LDPE for the example was a density of 0.92-0.922 g/cm³, a melt indexof 1.8-2.4, and an average MW of 80,000. The polymer was melted for twominutes. In the next two minutes asphaltene was added into the moltenpolymer. After complete addition of the filler, the mixing was continuedfor another six minutes. During the mixing, the temperature and torquewere constant. The blended mixtures were then hot pressed at 180° C.under a pressure of 9 MPa using Carver hot-press (Indiana, USA). Thesamples were kept in the hot stage for 5 minutes. Then it was cooled for10 more minutes. The relative amounts of LDPE and asphaltenes togetherwith the code name of each sample appear in Table 1.

TABLE 1 Relative amounts of LDPE and asphaltenes and code number of eachcomposite studied Sample LDPE:Asphaltenes (wt %) LD 100:0  LDA197.5:2.5  LDA2 95:5  LDA3 92.5:7.5  LDA4 90:10 LDA5 85:15

Characterization Fourier Transform Infra-Red (FTIR) Spectroscopy

For the characterization of the chemical structure of the pristine LDPEand its composites, FTIR spectroscopy was used. The instrument used wasan FTIR spectrophotometer of Perkin-Elmer, Spectrum One. The resolutionof the equipment was 4 cm⁻¹and the recorded wavenumber range was from450 to 4000 cm ⁻¹ and 32 spectra were averaged to reduce the noise.

Thermogravimetric Analysis (TGA)

To determine the thermal stability of the composition TG analysis wasperformed on a Pyris 1 TGA (Perkin Elmer, Massachusetts, USA) thermalanalyzer equipped with a sample pan made of Pt. Samples of about 5 mg-8mg were used. The samples were heated from ambient temperature to 600°C. at a heating rate 10° C./min, under a 20 ml/min nitrogen flow.

Differential Scanning Calorimetry (DSC)

Thermal properties of the composites were measured by DSC. Theinstrument used was the DSC-Diamond from Perkin-Elmer (Massachusetts,USA). The sample mass was approximately 5.5 mg in all measurements. Theexperimental conditions of the measurements included the followingsteps: Heat from 30° C. to 190° C. at 20° C./min; Hold at 190° C. for 2min; Cool from 190° C. to −40° C. at 20° C./min; Hold at −40 ° C. for 2min; and Heat from-40 to 190 at 20 ° C./min. All melting temperatureresults are from the second heating to eliminate thermal history of thesample. Crystallization was recorded during cooling from the melt.

X-ray diffraction (XRD)

X-ray diffraction (XRD) patterns of LDPE and its composites wereobtained from an XRD-diffractometer (model Richard Seifert 3003 TT,Ahrensburg, Germany) with a CuKa radiation for crystalline phaseidentification (λ=0.15405 nm for CuKa). The scanning range, 2θ, of thesamples was from 5° to 50°, at steps of 0.05 and counting time of 5 s.

Scanning Electron Microscopy

Scanning electron microscopy (SEM) images were taken with acceleratingvoltage of 15.00 kV (model Zeiss Supra 55 VP, Jena, Germany).

Tensile Mechanical Properties.

The tensile mechanical properties were studied on relatively thin filmsof the polymer or composites. Dumbbell-shaped tensile-test specimens(central portions, 5×0.5 mm thick, gauge length 22 mm) were cut from thesheets in a Wallace cutting press and conditioned at 23° C. and 55-60%relative humidity for 48 h. The stress-strain data were obtained with anInstron model BlueHill 2 tensile-testing machine (Massachusetts, USA),which was maintained under the same conditions and operated at anextension rate of 5 mm/min. The values of the yield stress, tensilestrength, and elongation at break were determined according to ASTM D1708-66. Five specimens were tested for each sample, and the averagevalues are reported.

Dynamic Mechanical Thermal Analysis (DMTA).

Thermal mechanical tests were done using a dynamic mechanical analysisinstrument (Perkin Elmer Diamond DMA Technology SII, Massachusetts, USA)in sinusoidal three-point bending mode. The vibration frequency was 1Hz, the stress 4000 mN and the amplitude 10 m μ. The temperature wasvaried from 25° C. to 130° C. with a scanning rate of 3° C./min in anitrogen atmosphere. Rod-like specimens were prepared with dimensions2×2×40 mm.

Results FTIR Spectra

The FTIR spectra of all samples appear in FIG. 1. The spectra of allsamples show the presence of the traditional absorption bands ofpolyethylene. These are: high intensity peaks at 2851 and 2921 cm⁻¹attributed to the vibration mode of the chain methylene (—CH₂) groups,(stretching of C—H bonds), at 1467 cm⁻¹ 102 bending vibrations ofsymmetric methylene groups (C—H) and at 721 cm⁻¹ 103 corresponding to—CH₂ rocking (deformation and elongation mode of CH₂ group).

In the composites almost the same spectra were recorded, since the samecharacteristic chemical groups appear in the asphaltenes as in LDPE andthey are mainly C—H bonds in either —CH₂ or —CH₃.

Melting and Crystallization Behavior

In order to study the melting behavior of pristine LDPE and all itscomposite materials, DSC thermograms were recorded and results obtainedduring the second heating appear in FIG. 2. The melting peaktemperatures and the total heat of fusion obtained from these curves arereported in Table 2. As it can be seen all curves are similar and mostof the samples melt at approximately 116° C. 201, except of LDA2 where aslightly higher value, 118° C. 202 was measured. In addition, ΔH_(m) ofthe composites is always lower than the pristine LDPE except for theLDA2 sample, where a value similar to LDPE was measured.

Crystallization of the samples was also recorded during cooling from themelt. Results appear in FIG. 3 and Table 2. Two exothermic peaks wererecorded, one is strong and sharp emerging at 91° C. 301 and the otheris small, rather like a broad shoulder, emerging at about 57° C. 302.This is an indication of existence of crystallites with variousthicknesses. Furthermore, smaller crystallites content (the shoulderpeak) is less than that of larger ones. These double crystallizationpeaks are also an indication of a high degree of branching found inLDPE. More branched chains form more defected and less stable crystalsthat form at lower temperature.

The lower melting enthalpy measured for the LDA5 sample was alsoreflected in lower total heat released during crystallization from thissample and as a result of lower crystallinity of the whole composite. Ifthe relative amount of the polymer in the composite is taken intoconsideration, the following equation providing the corrected degree ofcrystallinity, X_(c,cor) of each composite can be derived as:

$X_{c,{cor}} = {\frac{\Delta \; H_{m}}{\Delta \; H_{m}^{0}w}100}$

where, ΔH_(m) is the heat of fusion of LDPE and its composites, ΔH_(m) ⁰is the heat of fusion for 100% crystalline LDPE taken equal to 293.6 J/gand w is the weight fraction of LDPE in the composites.

From the corrected degree of crystallinity, values reported in Table 2,it seems that LDA2 composite has almost the same crystallinity withpristine LDPE, while all other composites have lower values. Therefore,it seems that the addition of asphaltenes in LDPE is beneficial to thecrystallization of LDPE only until the amount of 5%. Therefore, thisvalue seems to be the optimum concerning the nucleating effect ofasphaltenes in the LDPE matrix.

TABLE 2 Results from DSC measurements, Tm 

 melting peak temperature, T_(c) crystallization peak temperature,ΔH_(m) total heat during melting, ΔH_(c) total heat released duringcrystallization X_(c) degree of crystallinity and X_(c,cor) correcteddegree of crystallinity. Sample T_(m) (° C.) ΔH_(m) (J/g) T_(c1) (° C.)T_(c2) (° C.) ΔH_(cryst) (J/g) X_(c) (%) X_(c, cor) (%) LD 116.2 96.691.3 57.2 100.5 32.9 32.9 LDA1 114.6 84.7 92.0 58.1 93.3 28.8 29.6 LDA2118.0 92.0 90.8 56.9 99.8 31.3 33.0 LDA3 115.6 87.1 90.0 56.7 92.6 29.732.1 LDA4 116.6 80.8 91.6 57.0 90.3 27.5 30.6 LDA5 116.9 71.7 91.6 57.180.1 24.4 28.7

WAXD Examinations

FIG. 4 shows XRD patterns of pristine LDPE and its composites. Thecharacteristic diffraction peaks at 2θ: 22° (110) 301, 24° (200) 302 and36.5° (020) 303 are clear. A small peak at 20° 304 was also measured inall samples. LDPE filled with asphaltenes crystallizes with the samephase of the pristine polymer with however a significant variation ofthe intensity of the peaks between pristine LDPE and the composites. Thecrystallinity and crystal structure of the composites LDA1 and LDA2 werenearly identical. However, for composites LDA4 and LDA5 a broad peakappears at 2θ=22° 305 which overlaps the peak at 24° . The increase inthe intensity of the peaks of the LDA1 and LDA2 samples indicates anincrease in the crystalline nature of the composite at these relativeamounts.

The crystallite size (L) can be obtained by the Scherrer's formula fromthe half-width of (110) 301 diffraction peak:

$L = \frac{K\; \lambda}{b\; {\cos (\theta)}}$

where, K is a constant assumed to be 0.94 for Full Width at Half Maxima(FWHM) of spherical crystals with cubic symmetry, λ is the wavelength ofX-ray beam (0.154 nm), b is FWHM in radians and θ is the angle at thedominant peak (around)22° .

Results on the FWHM and the crystallite size, L estimated for allsamples appear in Table 3. It can be seen that the crystallite sizeincreases from LD to LDA2 and then decreases significantly to very lowvalues for LDA4 and LDA5. The reduction of crystallite size may beascribed to the hindrance of mobility of the LDPE chains by the presenceof large amounts of asphaltenes. This in turn is associated with thedecrease of local order within the polymer. From these data appears thatLDA2 with 5% asphaltenes appears to have the best performance concerningthe crystallinity of the mixture as it was also concluded from DSCmeasurements.

TABLE 3 Characteristic peaks and calculated crystallite size forpristine LDPE and its composites obtained from WAXD measurements. Sample2θ (°) FWHM (radians) L (nm) LD 19.9 22.0 24.1 36.8 0.0195 7.52 LDA120.0 22.0 24.2 36.5 0.0188 7.80 LDA2 19.9 21.9 24.1 36.7 0.0164 8.96LDA3 19.9 21.9 24.2 36.6 0.0210 7.04 LDA4 19.9 21.8 — 36.7 0.0733 2.01LDA5 19.8 21.75 — 36.5 0.0366 4.02

SEM Observations

SEM images of all LDPE/asphaltenes composites appear in FIG. 5A throughFIG. 5F. Higher agglomerates were observed with increased asphaltenecontent in samples LDA4 and LDA5.

Thermogravimetric Analysis

Thermal stability of neat LDPE and its composites with different amountsof asphaltenes appears in FIG. 6A. The corresponding differential TGcurves appear in FIG. 6B. As it can be seen, degradation completes inone step in all different samples and all composites present curvesshifted to higher temperature values compared to pristine LDPE. Thismeans that all composites have better thermal stability compared toLDPE. LDPE thermally degrades to volatile products leaving a residue ofaround 2.7% at 600° C. through a radical chain process, whose onset(T₂%) and maximum weight loss rate temperature (T_(p)) are around 422°C. and 495° C., respectively. The initial decomposition temperature ofall composites is shifted to higher temperatures compared to pristineLDPE (T_(2%) in Table 4) confirming the protecting role of theasphaltenes in relation to the thermal stability of LDPE. The higherT_(2%) temperature was recorded in the LDA1 composite, meaningincorporation of 2.5% asphaltenes in the LDPE matrix. Moreover, from thetemperatures where degradation reaches 50% (T_(50%)), as well as wherethe peak in the degradation rate appears (T_(p)), it seems that bestthermal stability is achieved in the LDA2 or LDA3 composite, i.e. with5% or 7.5 wt % of the additive. It seems that the addition ofasphaltenes at this concentration fomis a protective layer (thermalshield) around the polymer which delays the degradation induced by heatand acts as a thermal barrier limiting the emission of the gaseousdegradation products, resulting in an increase in the theiiiialstability of the material. Therefore, the most effective protectionseems to be achieved with an amount near 5wt %. Higher amount ofasphaltene added (i.e. 10% to 15%) reduces the thermal stability of thecomposite. It is believed that the homogeneous dispersion of asphaltenesresults in trapping the volatilizing matrix from escape to theatmosphere. Higher amount of asphaltenes, form agglomerates resulting ina non-homogeneous mixture.

TABLE 4 Temperature where thermal degradation starts (T_(2%)), at 50%conversion (T_(50%)) and at the degradation peak (T_(p)) as well asresidue at 600° C. of pristine LDPE and LDPE/asphaltenes composites.Sample T_(2%) T_(50%) T_(p) Residue at 600° C. (%) LD 422 488 495 2.7LDA1 432 498 500 5.0 LDA2 430 500 501 4.4 LDA3 428 499 502 7.7 LDA4 426496 499 8.0 LDA5 429 497 498 8.5

Mechanical Properties

Tensile mechanical properties of LDPE and LDPE/asphaltenes compositesare illustrated in Table 5. From the measurements it seems that thehighest tensile strength was measured for the LDA2 composite, accordingto previous findings. When a high content of asphaltene was incorporatedits dispersion in the LDPE matrix becomes more difficult resulting inlower tensile strength. It seems that the best additive-matrix adhesionis obtained at a relative amount of asphaltene equal to 5 wt % (FIG. 7).

TABLE 5 Tensile mechanical properties from Instron analysis and storagemodulus from DMA of pristine LDPE and its composites with asphaltenes.Tensile strength Elongation at Storage Modulus, E′(GPa) Sample (MPa)break (%) at 23° C., from DMA LD 9.25 ± 0.91 149.0 ± 14 0.96 LDA1 9.56 ±0.87 153.1 ± 14 1.17 LDA2 9.76 ± 0.90 168.3 ± 14 1.06 LDA3 9.20 ± 0.82133.6 ± 14 0.71 LDA4 9.42 ± 0.94 134.8 ± 14 0.61 LDA5 9.05 ± 0.94 136.6± 14 0.57

Dynamic Thermo-Mechanical Properties Using DMA

The variation of storage modulus, E′, loss modulus, E″ and phase angle,tanδ=E″/E′ obtained from DMA measurements appear in FIG. 8A, FIG. 8B,and FIG. 8C. Samples LD, LDA1 and LDA2 appear to have higher values ofthe storage and loss modulus compared to LDA3, LDA4 and LDA5. The valuesof E′ at room temperature (around 22° C.) for all studied samples areincluded in Table 5. It is seen that LD, LDA1 and LDA2 have a valuearound 1 GPA much higher than the others. In LDPE three relaxations arenormally observed, identified as α, β and γ in order of decreasingtemperature. The α-relaxation is normally observed between 30° C. andthe melting point, the β-relaxation between −55° C. and 25° C., whilethe γ-relaxation between −145° C. and −95° C. In FIG. 8B one peak isobserved at around −4° C., associated with the β-relaxation of LDPE.From FIG. 8A, FIG. 8B, and FIG. 8C no results can be obtained for the αand γ relaxations. Results on the β-relaxation are included in Table 6.It seems that all samples except of LDA1 and LDA5 have almost the sameβ-relaxation temperature.

TABLE 6 Characteristic thermal transitions estimated from the peak intanδ Sample β-relaxation (° C.) LD −3.5 LDA1 −6.0 LDA2 −4.0 LDA3 −3.0LDA4 −3.0 LDA5 0.0

Several composites of LDPE with different amounts of asphaltenes wereprepared by the melt-mixing technique. From the analysis of theirproperties, it the data from the example indicate that the addition ofasphaltenes:

-   -   May not alter the chemical characteristics of LDPE as measured        by FTIR measurements showing the same absorbance peaks    -   May increase the thermal stability of LDPE by almost 10° C. as        determined by TGA measurements; wherein degradation of the        composites was shifted to higher values.    -   May retain almost the same melting and crystallization        temperature, while decreases the enthalpy of fusion and        crystallization, except of LDA2 sample, resulting in decreased        relative degree of crystallinity, as it comes from DSC thermal        scans.    -   May retain the same crystalline phase as measured by WAXD        measurements. High amounts of asphaltenes tend to disturb the        crystalline state while the higher crystallite size was measured        for the LDA2 sample.    -   May not alter significantly the mechanical tensile properties,        while only LDA2 was found to have improved tensile strength.    -   May increase the storage modulus only for LDA1 and LDA2, while        these properties seem to deteriorate when the amount of        asphaltenes added is very high.

Overall, the example presents a case in which the weight percentage ofasphaltenes that may be added in the LDPE around 5 wt % resulting in thebest dispersion in the polymeric matrix, larger crystallite size,enhanced thermal stability, highest relative degree of crystallinity andimproved mechanical tensile or thermo-mechanical properties.

1: A low density polyethylene-asphaltene composition comprising: anasphaltene, wherein the asphaltene is extracted from at least one of aheavy atmospheric residue, an oil sand, bitumen, and a biodegraded oil,and a weight percent of the asphaltene is 0.1%-25% relative to a totalweight of the composition; and a low density polyethylene polymer with adensity of 0.9 g/cm³-0.95 g/cm³; wherein the asphaltene and the lowdensity polyethylene polymer are unifoimly dispersed throughout the lowdensity polyethylene-asphaltene composition, the low densitypolyethylene-asphaltene composition has a weight loss onset 4° C.-20° C.higher than an average weight loss onset of the low density polyethylenepolymer, and the low density polyethylene-asphaltene composition has adegree of crystallinity of 27%-34%. 2: The low densitypolyethylene-asphaltene composition of claim 1, wherein the low densitypolyethylene-asphaltene composition has a peak melting point of 110°C.-123° C. 3: The low density polyethylene-asphaltene composition ofclaim 1, wherein the low density polyethylene-asphaltene composition hasa heat of fusion of 84 J/g-93 J/g. 4: The low densitypolyethylene-asphaltene composition of claim 1, wherein the low densitypolyethylene-asphaltene composition has a storage modulus of 8%-25%greater than an average storage modulus of the low density polyethylenepolymer at a temperature of 22° C.-25° C. 5: The low densitypolyethylene-asphaltene composition of claim 1, wherein the low densitypolyethylene-asphaltene composition has a tensile strength of 3%-5%greater than an average tensile strength of the low density polyethylenepolymer. 6: The low density polyethylene-asphaltene composition of claim1, wherein the asphaltene comprises 0.9 to 1.8 wt % of nitrogen, 7.5 to8.1 wt % of sulfur, 1.9 to 2.6 wt % of oxygen, relative to the totalweight of the asphaltene. 7: The low density polyethylene-asphaltenecomposition of claim 1, wherein a weight percent of the low densitypolyethylene polymer is 75%-99.9% relative to the total weight of thecomposition. 8: A method to prepare a low densitypolyethylene-asphaltene composition comprising: melting a low densitypolyethylene polymer to form a melted low density polyethylene polymer;adding an asphaltene to and mixing the melted low density polyethylenepolymer at a mixing temperature of 165° C.-200° C. to form a melted lowdensity polyethylene-asphaltene blend; pressing the melted low densitypolyethylene-asphaltene blend to form a pressed low densitypolyethylene-asphaltene blend; and cooling the pressed low densitypolyethylene-asphaltene blend to a cooled temperature of 22° C.-30° C.to form the low density polyethylene-asphaltene composition; wherein theasphaltene is 0.1%-25% relative to a total weight of the composition. 9:The method of claim 8, wherein the low density polyethylene polymer ismelted at a melting temperature of 165° C. to 200° C. 10: The method ofclaim 8, wherein the melted low density polyethylene-asphaltene blend ispressed for a duration of 1 min-10 min. 11: The method of claim 8,wherein the melted low density polyethylene-asphaltene blend is pressedat a pressing temperature of 175° C.-200° C. 12: The method of claim 8,wherein the melted low density polyethylene-asphaltene blend is pressedat a pressure of 7 MPa-10 MPa. 13: The method of claim 8, wherein theasphaltene is extracted from at least one of a heavy atmosphericresidue, oils sands, bitumen, and biodegraded oils. 14: The method ofclaim 8, wherein the asphaltene is a semi-crystalline solid. 15: Themethod of claim 8, wherein the low density polyethylene-asphaltenecomposition has a peak melting point of 110° C.-123° C. 16: The methodof claim 8, wherein the low density polyethylene-asphaltene compositionhas a degree of crystallinity of 27%-34% and has a heat of fusion of 84J/g-93 J/g. 17: The method of claim 8, wherein the low densitypolyethylene-asphaltene composition has a weight loss onset 4° C.-20° C.higher than an average weight loss onset of the low density polyethylenepolymer. 18: The method of claim 8, wherein the low densitypolyethylene-asphaltene composition has a storage modulus of 8%-25%greater than an average storage modulus of the low density polyethylenepolymer at a temperature of 22° C.-25° C. and the low densitypolyethylene-asphaltene composition has a tensile strength of 3%-5%greater than an average tensile strength of the low density polyethylenepolymer. 19: The method of claim 8, wherein the asphaltene comprises 0.9to 1.8 wt % of nitrogen, 7.5 to 8.1 wt % of sulfur, 1.9 to 2.6 wt % ofoxygen, relative to the total weight of the asphaltene. 20: A lowdensity polyethylene-asphaltene composition consisting of: anasphaltene, wherein the asphaltene is extracted from at least one of aheavy atmospheric residue, an oil sand, bitumen, and a biodegraded oil,and a weight percent of the asphaltene is 0.1%-25% relative to a totalweight of the composition; and a low density polyethylene polymer with adensity of 0.9 g/cm³-0.95 g/cm³; wherein the asphaltene and the lowdensity polyethylene polymer are uniformly dispersed throughout the lowdensity polyethylene-asphaltene composition, the low densitypolyethylene-asphaltene composition has a weight loss onset 4° C.-20° C.higher than an average weight loss onset of the low density polyethylenepolymer, and the low density polyethylene-asphaltene composition has adegree of crystallinity of 27%-34%.